Washable centrifuge

ABSTRACT

A centrifuge of the type which has a rotatable drum and a rotatable conveyor within the drum is provided with a casing that is sealed water-tight around the centrifuge. Inlets and outlets for washing liquid are provided in the casing so that it can be filled to a level which at least substantially fills the centrifuge for washing it, and then may be drained.

United States Patent [191 Merzenich 1 [111 3,802,621 [45 1 Apr.9, 1974 WASHABLE CENTRIFUGE [75] Inventor: Konrad Merzenich, Hoffnungsthal,

Germany [73] Assignee: Bird Machine Company, Inc., South Walpole, Mass.

[22] Filed: Mar. 5, 1973 [21] Appl. No: 338,157

[30] Foreign Application Priority Data Mar. 4, 1972 Germany 2212178 [52] US. Cl. 233/7, 2.33/1 D [51] Int. Cl B04b 1/00 [58] Field of Search 233/1 R, l A, l D, 7, 27,

[56] References Cited UNITED STATES PATENTS Ferney 233/7 3,279,687 10/1966 Amero 233/7 3,428,248 2/1969 Andresen et al.... 233/7 927,059 7/1909 Kuchs 233/7 Primary Examiner-George H. Krizmanich Attorney, Agent, or Firm-Edgar H. Kent 57 ABSTRACT A centrifuge of the type which has a rotatable drum and a rotatable conveyor within the drum is provided with a casing that is sealed water-tight around the centrifuge. Inlets and outlets for washing liquid are provided in the casing so that itican be filled to a level which at least substantially fills the centrifuge for washing it, and then may be drained.

4 Claims, 1 Drawing Figure WASHABLE CENTRIFUGE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a centrifuge, especially a centrifuge of the type which has a rotatable drum that is solid or partly or all a screen and which is surrounded all around by a casing, in which drum is a coaxiallymounted screw conveyor which rotatesat a different speed to discharge solid matter.

2. Description of the Prior Art Because of health regulations, the utilization of such centrifuges in the area of foodstuff or drug production and in related areas of application requires a careful cleaning of all machine parts that come into contact with the substances processed in the machine. Hitherto, this could be accomplished only by a method of construction in which the casing surrounding the centrifuge drum was disassembled and in which the centrifuge drum was so constructed that it could also be disassembled in order that the inner wall of the solid or screening drum and the solid-matter discharge screw conveyor mounted in the drum were accessible and could be cleaned. However, this required timeconsuming assembly operations.

SUMMARY OF THE INVENTION An object of this invention is to provide a centrifuge of the aforesaid type which can be cleaned even under strict health requirements without the need for bothersome disassembly and reassembly operations. Another object is to provide such a centrifuge which can be made at little additional cost as compared with existing centrifuges of this type.

According to the invention, the problem is solved in that the openings in the ends of the casing for the drum shaft are provided with seals and the casing is provided with at least one inflow opening and at least one outflow opening for a washing liquid. Because of this construction, it is possible to fill with washing liquid the entire volume of the centrifuge lying within the casing and then to drive the drum and the solid-matter discharge screw conveyor, which is connected to the drum by a suitable gear unit, at a low rotation speed with periodic reversal of the direction of rotation if necessary. If fresh washing liquid is now fed in continuously at one side of the machine while the contaminated liquid continuously runs off, then, due to the intense agitation of the washing liquid both within the casing and also inside the drum caused by the rotation of the drum, the ma chine is completely cleaned in a relatively short time even in otherwise practically inaccessible corners of the casing. Seals between the drum and conveyor. shafts prevent the water from escaping between them and a seal around the feed pipe prevents water escaping around it.

In a preferred embodiment of the invention, at least one outflow opening preferably is arranged on top of the casing and inflow lines empty into the closeable filtrate discharge pipe and also into the closeable solidmatter discharge. pipe of the casing. Taking advantage of the fact that the solid-matter discharge pipe is situated at one end of a machine and the filtrate discharge pipe at the other end, this arrangement assures a desired flow through the centrifuge, especially with the arrangement of several outflow openings on the casing BRIEF DESCRIPTION OF THE DRAWING The single FIGURE of the drawing shows, partly in longitudinal section, partly in side elevation, a centrifuge of the type concerned with solid drum, embodying the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing shows a centrifuge which is washable in accordance with the invention having a solid or closed drum, but as previously stated the drum may be partly or all a screen. Centrifuge drum 1 is rotated at a high rotation speed, and within the drum a solid-matter discharge screw conveyor 2 is rotated at a different rotation speed. The centrifuge drum is driven, for example, by a belt pulley 3, while the solid-matter discharge screw conveyor 2 is driven for its part by the centrifuge drum via a suitable gear unit, for example, a planetary gear unit 4. The centrifuge drum has solid-matter discharge openings 5 at its conically tapered end and filtrate overflow openings 6 at the opposite end. The ad'- mission of the suspension to be centrifuged occurs through afeed pipe 7 which projects coaxially into the interior of the solid-matter discharge screw conveyor while, in the region of the outlet orifice of the feed pipe, openings 8 are provided in the support of the solid-matter discharge screw conveyor for the suspension to be treated. I

The centrifuge drum is surrounded all around by a casing 9 which below the centrifuge drum is provided with a solid-matter discharge pipe 10 at the solidmatter discharge end of the drum and with a filtrate discharge pipe 11 at the filtrate outlet end of the drum.

According to the invention, the openings for the drum shafts l2, 13 in the casing 9 are each completely sealed off by a seal 14. Inflow lines 15 and 16 for a washing liquid empty into the solid-matter discharge pipe 10 and also into the filtrate discharge pipe 11, these lines being provided with valves 23 and 24. Below the discharge of the washing-liquid. inflow lines 15 and 16, the spouts 10 and 11 are provided with shutoff devices 17 and 18. Furthermore, outflow lines 19 and 20 which are also provided with valves 21 and 22 are arranged on the top of the casing approximately in the region of the drum ends. Seals 25, 26 are provided between drum shafts 12, 13 and conveyor shafts 27, 28 to prevent outflow of water between the shafts, and these may be the usual grease seals at the end of bushings 29 between the two shafts. A seal (not shown) is provided around feed pipe 7 where it enters the outer end of conveyor shaft 27.

Possible washing liquids include hot water, water with cleaning additives or even, depending on the nature of the substances treated in the centrifuge, lye and acid solutions, so that besides the purely mechanical cleaning action, possibly present deposits or residues are chemically decomposed while, by means of the special arrangement of the inflow and outflow lines, a suitable manipulation and control of the inflow and outflow valves also enables the corners of the casing, drum and screw conveyor support to be completely washed free.

The cleaning of the centrifuge constructed according to the invention is accomplished in the following manner. After the shutoff devices 17 and 18 in the discharge pipes are first closed, by opening the valves 23 and 24 in the washing-liquid inflow lines 15 and 16 and opening valves 21 and 22 to permit air escape, the casing, the centrifuge drum and the inner volume of the screw conveyor support which comes into contact with the substance to be centrifuged are completely filled with washing liquid so that valves 21 and 22 may be closed. The drum fills through openings and 6 while the feed chamber of the conveyor support fills through openings 8. The drum now is rotated at a rotation speed which is relatively small in comparison with the operating rotation speed so that, due to the resulting intense agitation, all parts of the centrifuge that come into contact with the centrifuged substance are washed and possibly present deposits are decomposed. In doing this, it is effective to reverse the direction of rotation from time to time. After some time, one of the outflow valves is opened, for example, the outflow valve 22, while the outflow valve 21 remains closed and also the inflow valve 24 is closed while inflow valve 23 remains open so that the machine preferably with continuous rotation of the drum is flowed through diagonally by washing liquid. After a suitable washing time the inflow valve 24 and the outflow valve 21 are then opened while inversely the valves 22 and 23 are closed so that the other end of the machine is washed out crosswise. It is advantageous here if the suspension admission pipe 7 is also provided with an inlet for washing liquid so that the inflow pipe 7 can also be washed out and fresh washing liquid can be introduced into the interior of the screw-conveyor support.

Depending on the size of the machine, as also illustrated in the drawing, the casing 9 can additionally be provided with a third valved inlet 30 for washing liquid on its bottom between the two discharge pipes so that the middle region of the casing also can be supplied with fresh washing liquid. With the middle region of the casing bottom formed as shown, a valved drain pipe 31 is provided therein.

When washing has been completed, shut-off devices 17 and 18, and valved outlet 31 if provided, are

opened. Valves 23 and 24, and valved inlet 30 if provided, are closed. Valves 21 and 22, which are arranged to open outflow lines 19 and 20.to atmosphere as well as to the water outflow connection, are opened to atmosphere. The water in the casing now completely drains out its bottom except for a small amount left in the centrifuge drum, which is automatically removed when the machine is started up with slurry feed.

It will be appreciated that while it is preferred to arrange inlets and outlets to enable the casing to be completely filled with washing liquid as shown, it is sufficient for purposes of the invention if the arrangement enables the casing to be filled to a level such that the drum is at least substantially filled with liquid through its discharge ports.

I claim:

1. A centrifuge having a rotatable drum, a rotatable conveyor within the drum, means for rotating said drum and said conveyor at different speeds, a casing completely surrounding said drum, said drum having one or more openings from the interior thereof into said casing, means forming liquid-tight seals between the exterior of said casing and the interior and exterior of said drum, inlet and outlet means in said casing for respectively supplying washing liquid into and discharging it from said casing and arranged to enable said casing to be filled with said liquid to a level at which said drum at least substantially fills with the liquid through said openings, and thereafter to enable said liquid to be drained from said casing, and means for closing and opening said inlet and outlet means.

2. A centrifuge according to claim 1 wherein said outlet means includes at least one outlet from said casing above said drum, and at least one outlet at the bottom of said casing, and said inlet means includes at least one inlet to said casing below said drum.

3. A centrifuge according to claim 2 wherein said outlet means includes an outlet from said casing above each end of said drum, and said inlet means includes an inlet to said casing below each end of said drum.

4. A centrifuge according to claim 1 wherein said outlet means includes outlets for the respective products of centrifuging adjacent opposite ends of the bottom of said casing. 

1. A centrifuge having a rotatable drum, a rotatable conveyor within the drum, means for rotating said drum and said conveyor at different speeds, a casing completely surrounding said drum, said drum having one or more openings from the interior thereof into said casing, means forming liquid-tight seals between the exterior of said casing and the interior and exterior of said drum, inlet and outlet means in said casing for respectively supplying washing liquid into and discharging it from said casing and arranged to enable said casing to be filled with said liquid to a level at which said drum at least substantially fills with the liquid through said openings, and thereafter to enable said liquid to be drained from said casing, and means for closing and opening said inlet and outlet means.
 2. A centrifuge according to claim 1 wherein said outlet means includes at least one outlet from said casing above said drum, and at least one outlet at the bottom of said casing, and said inlet means includes at least one inlet to said casing below said drum.
 3. A centrifuge according to claim 2 wherein said outlet means includes an outlet from said casing above each end of said drum, and said inlet means includes an inlet to said casing below each end of said drum.
 4. A centrifuge according to claim 1 wherein said outlet means includes outlets for the respective products of centrifuging adjacent opposite ends of the bottom of said casing. 